3D Graphene-Oxide Spheres for Supercapacitors

Supercapacitors and electrochemical capacitors show great potential for large-scale energy storage. They possess unique advantages which include rapid charge–discharge rate, long cycle life, and ultrahigh power density. They are ideal for use in fast energy storage and delivery, such as required for smart power grids and hybrid electric vehicles. However, the shortcomings related to the low energy density of such batteries require attention to enable the performance to be boosted by the increase of the specific capacitance of the electrode material.

General, the surface functionality, specific surface area, pore volume, and pore size distribution of an electrode material all influence the resulting specific capacitance. Moreover, to achieve a high volumetric capacitance and rate capability in a material, the intrinsic density of the electrode and the electrical conductivity play an important role. Therefore, robust methods of synthesis to address these needs are required.

Many materials are investigated, including metal–oxide/hydroxide complexes to inorganic porous structures of polymers, and many more. While in recent years, graphene-oxide (GO) based carbons emerged as promising materials due to their highly tunable surface chemistry.

An effective synthesis strategy via a flash-freezing and freeze-dry approach is presented, in a recently published article. The method enables 3D GO structures to be produced that exhibit fully accessible hierarchical porous networks. These porous GO materials show enhanced performance as supercapacitors, exhibiting a 30–50% enhancement in the charge storage capacity compared with unprocessed GO powder samples. This approach contributes to the further development of GO-based structures for energy storage technologies.